Germany's defence minister has been formally stripped of his Dr title after his university ruled he had "seriously violated" its standards by submitting a thesis riddled with plagiarisms.

Karl-Theodor zu Guttenberg, who recently overtook Angela Merkel as Germany's most popular politician in a poll, admitted in the German parliament on Wednesday that he had made "serious errors" in his academic work, which he completed in 2006 while already an MP.

He said he had been overwhelmed by writing the work while starting a family and launching his political career and that he had been "arrogant" to believe he could juggle it all at the same time.

"I did not deliberately cheat, but made serious errors," said Guttenberg to loud jeers in the chamber.

Before coming clean in the Bundestag, the 39-year-old wrote a contrite letter to his alma mater, the University of Bayreuth, asking them to revoke his doctorate.

Within 24 hours his wish was granted, and on Wednesday night the university issued a statement confirming that Guttenberg could no longer call himself Dr.

Guttenberg, now dubbed Googleberg, initially tried to ride out the storm after the scandal came to light last week, dismissing the allegations of plagiarism as "fanciful".